Hotels dealing with work and academic conventions, and of course weddings generally expect to provide higher quality food at a higher price point than conventions require. But if you explain your needs they can generally provide simple options at reasonable prices and still make money.
For breakfast, ask for a buffet and allow attendees to seat themselves. Queues quickly form if the staff try and seat each singleton on their own table. The hotel will usually check names against a list of staying guests to stop free-loading. "There are never enough mushrooms" is a common fannish cry. Get extended hours on the morning after the night before, but some people like a 7.30 breakfast.
For daytime food, offer a buffet served by hotel staff with jacket potato+fillings, curry etc. Remember vegan options.
Have bar food and sandwiches. Quick food is important for busy people.
Late night bacon butties are popular.
Allow people to pay with groats.
The number of people eating in the hotel depends on the nearby alternatives.
Some people will pay full price in the hotel restaurant, don't try to shut it down.
Conventions used to hold banquets, often in conjunction with award ceremonies, but a succession of rubber-chicken events have made this less popular. Don't make attending the banquet a condition for seeing the awards. Novacon replaced their Dead Dog Party with a beer tasting (bring 3 interesting bottles, or pay £5) with optional buffet meal. Its a popular event with near universal take up of the food.